U.S. Pat. No. 4,787,924 discloses a portable handheld work apparatus having an internal combustion engine wherein means are provided for setting a summer operation and a winter operation. The carburetor is mounted in a compartment covered by a filter element and two separate air inlet openings are provided for the inflow of combustion air. These inlet openings can be alternately opened or closed by a blocking wall. During summer operation, the blocking wall is so positioned that it closes an opening connecting the engine compartment to the carburetor compartment and clears an opening connected to the outside of the apparatus housing so that external air is supplied to the carburetor as combustion air. During winter operation, the opening to the outside is closed and the opening to the engine compartment is open so that air, which is heated by the cooling ribs of the engine, is supplied to the carburetor as combustion air. This publication is silent as to the cooling of the cylinder and the guidance of the cooling airflow at the cooling ribs.